Resilient cities - Hong Kong report: extreme heat

Causes of extreme heat

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The concept of green building has been embraced by various construction projects in both the public and private sectors. The on-going Hung Shui Kiu New Development Area (“NDA”) located in the New Territories is a good illustration of how the concept of green building can be incorporated into large scale development projects. One of the guiding principles of the NDA is “Creating a Green Living and Working Environment”, which places emphasis on green building and environmentally- friendly technologies. Among other things, the NDA provides environmentally- friendly transport modes and incorporates an efficient and safe pedestrian walkway and cycling networks. It also capitalises on existing landscape resources such as river channels and green mountain backdrops, and promotes sustainable waste and water management. In preparation for this report, Clyde & Co had the chance to discuss with Mr. Derrick H.C. Ho, Research Assistant Professor in the Department of Urban Planning and Design at the University of Hong Kong on the topic of green building. Mr. Ho highlighted a number of challenges in relation to green building in Hong Kong. Hong Kong is known for having a high building density which measures the concentration of building mass in a given geographical area. This means that there is limited space available in Hong Kong for new green buildings to be constructed.

ADAPTING TO EXTREME HEAT

Safety is another important concern. In May 2016, the whole rooftop of a sports centre at the City University of Hong Kong collapsed. 45 Fortunately, only three people were injured. This incident could have been catastrophic. Notably, the rooftop was green and covered by extensive vegetation. In a press report regarding the collapse, it was stated that there were discrepancies between data on the original loading capacity of the roof. It is believed that the collapse was due to the rooftop being overloaded as contractors relied on inaccurate data in adding green features to the existing rooftop. As can be seen, one of the key challenges in developing green buildings is to ensure the stability and safe construction of different structures. Another practical challenge of promoting green building in Hong Kong is the costs and expenses that are involved. Sustainable materials which help reduce carbon emission are costly and may make any implementation difficult. Effective sustainable development also requires careful planning by knowledgeable individuals (e.g. surveyors, experts). In addition to being a time-consuming process, engaging knowledgeable individuals can be expensive.

Extreme heat warning The HKO maintains a Hong Kong Heat Index in order to assess and monitor the severity of extreme heat.Where necessary, the HKO will issue “very hot” weather warnings (temperatures in excess of 33 ° C with humidity of over 80%) to enable the public to take necessary precautions. According to the HKO guidelines, when a “very hot” weather warning is issued, the public is recommended to drink plenty of water and avoid over-exertion when engaged in outdoor work or activities. The HKO also advises the public to pay attention to the health and wellbeing of elderly persons or persons with chronic medical conditions staying alone. Additionally, in order to minimise the adverse impact of extreme heat, the Home Affairs Department maintains air- conditioned community centres which are open to the public on extremely hot days.

Infrastructure resilience  Hong Kong has generally been performing well in terms of infrastructure resilience. In particular, given Hong Kong experiences tropical cyclones and rainstorms on a regular basis, it has developed robust infrastructure and management systems to deal with heavy rain, strong winds, landslides and flooding. In view of rising temperatures, extreme heat has increasingly been taken into account in designing infrastructure in Hong Kong. A prime example is Verbena Heights, a public housing project in Tseung Kwan O, which is well-known for its extensive use of greenery and specific design to enhance air circulation. This mitigates the wall effect and ensures residents enjoy natural ventilation, thus reducing the need to rely on air conditioning as a means of cooling. Verbena Heights received a silver medal from the Hong Kong Institute of Architects for its environmentally-conscious design.

45 https://www.bd.gov.hk/en/whats-new/press-releases/2017/0531A-buildings-department-releases- final-investigation-report-on-roof-structure-collapse-at-cityu-sports-hall.html

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